Method and apparatus for automatically corner-breaking the side flange edges of paperboard blanks

ABSTRACT

The invention contemplates apparatus and a method for automatically corner-breaking the side-flange edge folds of a paperboard blank having a central-panel area contiguous to and integral with longitudinally opposed side-flange areas. First pinch-roll means accepts flat stock, pinches the same to cornerbreak at a first desired alignment, and passes the entire blank to arresting and positioning means on the other side of the first pinch-roll means. When thus arrested, the blank is positioned adjacent second pinch-roll means, which is caused to accept and pinch the blank to corner-break at a second desired alignment. The blank passes through the first and second pinch-roll means in a continuous path of motion, interrupted only for displacement reversal when positioned for passage through the second pinchroll means. In the specific form shown, the first and second pinch-roll means collectively comprises three rollers, wherein the central roller coacts with one of the other rollers to define the first pinch-roll means, and wherein the central roller coacts with the remaining roller to define the second pinch-roll means.

rUnited States Patent [191 Ganz [ July 17, 1973 METHOD AND APPARATUS FORAUTOMATICALLY CORNER-BREAKING THE SIDE FLANGE EDGES OF PAPERBOARD BLANKSl76| Inventor: Robert H. Ganz,8 Ridge (rest Road, Saddle River, NJ.

221 Filed: July 28, 1971 21 Appl.No.: 166,757

93/39 R, 49 R, 49 M, 52, 62, 84 R; 53/48, 196; 270/62, 67, 80, 81, 83,84

[56] References Cited UNITED STATES PATENTS 1,867,909 7/1932 Deligianeset al. 270/67 X 2,401,]03 5/]946 Preston 270/67 3,055,276 9/1962 Millich93/49 M Primary Examiner-Robert L. Spruill Attorney-Sandoe, Hopgood &Calimafde [57] ABSTRACT The invention contemplates apparatus and amethod for automatically corner-breaking the side-flange edge folds ofapaperboard blank having a central-panel area contiguous to and integralwith longitudinally opposed side-flange areas. First pinch-roll meansaccepts flat stock, pinches the same to corner-break at a first de siredalignment, and passes the entire blank to arresting and positioningmeans on the other side of the first pinch-roll means. When thusarrested, the blank is positioned adjacent second pinch-roll means,which is caused to accept and pinch the blank to corner-break at asecond desired alignment. The blank passes through the first and secondpinch-roll means in a continuous path of motion, interrupted only fordisplacement reversal when positioned for passage through the secondpinch-roll means. In the specific form shown, the first and secondpinch-roll means collectively com prises three rollers, wherein thecentral roller coacts with one of the other rollers to define the firstpinchroll means, and wherein the central roller eoacts with theremaining roller to define the second pinch'roll means.

18 Claims, 14 Drawing Figures INVENTOR foam PAINTED- vsminlun;

PAH-INTE JUL 1 1491s SHEET 2 [IF 4 INVENTOR BEPrAK Qpu/ METHOD ANDAPPARATUS FUR AUTOMATICALLY CORNER-BREAKING THE SIDE FLANGE EDGES OFPAPERBOARD BLANKS This invention relates to packaging machinery andmethods and has particular application to such machines and methods asare concerned with plastic shrink-wrapping of clusters of articles, asfor example, two-by-three clusters of like cylindrical containers.lllustrative machines and methods of the character indicated aredisclosed in great detail in my copending application Ser. No. 47,996,filed June 22, 1970, and now US. Pat. No. 3,660,961. Reference is madeto said application for an understanding of the'overall packagingoperation.

In said application, mention is made, for each cluster, of the optionalinclusion of a flanged paperboard top or panel extending over the topsof containers in the cluster, with the flanges bent around opposedlateral top corner edges of the cluster and extending a short distancedownward. When the surrounding shrinkableplastic sheet envelops thecluster and its paperboard panel top, shrink action clamps thepaperboard flanges against adjacent upstanding opposed sides of thecluster. The paperboard panel serves the functions of reinforcing andstabilizing the package, while providing an extensive area for carryingthe manufacturers identification, dress, and message.

The present invention is particularly concerned with the means andmethod by which paperboard panels of the character indicated areautomatically conditioned, from flat-blank status, into corner-brokenflangedefining status, whereby panels are readily handled in aproduction shrink-packaging operation.

It is, therefore, an object of the invention to provide an apparatus andmethod whereby flat paperboard panel blanks may be automaticallycomer-broken, fold-conditioned and fed into a continuously operativeshrinlowrap machine, for inclusion in the wrapped package.

Another object is to achieve the above object without displacing ormodifying any existing part of the shrinkwrapping part of the machine.

A further object is to achieve the above objects without interrupting orretarding the smooth and continuous high-speed operation of theshrink-wrapping machine.

It is also an object to provide apparatus meeting the above objects andaccepting flat blank stock in quantity close to the region ofplastic-sheet feeding into a machine of the character indicated.

Other objects and various further features of novelty and invention willbe pointed out or will occur to those skilled in the art from a readingof the following specification, in conjunction with the accompanyingdrawings. In said drawings:

FIG. I is a simplified view in side elevation of operative parts of theinvention, certain portions being broken-away and in vertical section;

FIG. 2 is a view taken at 2-2 in FIG. 1, to show a work-piece, andtransfer and positioning means for the same;

FIGS. 3 through 7 are like fragmentary simplified views to illustrate,in a succession of steps, the Opera.- tion of the invention;

FIG. 8 is a fragmentary view, as :in FIG. 1, to illustrate a final stepof the invention, and its relation to a part of a cluster-wrappingmachine;

FIG. 9 is a view from 9--9 in FIG. 1, being a section through sideframes which are omitted from FIG. 1;

FIG. 10 is a view from l0-l0 in FIG. 9;

FIG. 11 is a simplified fragmentary view of operating parts, taken at11-11 in FIG. 10;

FIG. 12 is a view along the line 1212 of FIG. 11, certain parts beingshown in full elevation and others in section;

FIG. 13 is a view similar to FIG. 1 l, but showing parts as taken at thestepped alignment 13-13 of FIG. 10; and

FIG. 14 is a simplified perspective view, partly broken away, to showthe relation of operative parts of FIGS. 11 to 13.

Referring to FIGS. 1, 2 and 8 of the drawings, the invention is shown asan attachment to a shrink-wrap machine of the character shown anddescribed in said application, and here only briefly alluded to. Theconveyor system of such machine will be understood to include anincoming stretch 10 (FIG. 8), comprising a horizontalspan of linkscontinuously driven by sprockets (not shown) but synchronized withshrink-wrap functions and with paperboard-handling functions of theinvention. In the sense of FIG. 8, conveyor motion is from left toright, and conveyor 10 is shown for that portion of its length whichserves like clusters J-K-L-M- N of containers to be packaged, theultimately wrapped package A being shown to the right of the conveyorbreak, in FIG. 8; clusters not shown at the break between clusters A andJ will be understood to be undergoing shrink-wrap operations describedin said patent application. As in said application, each cluster maycomprise a 2 X 3 six-pack of cylindrical beverage containers; for theside elevation shown, only the near two containers of each such clrusterare visible, the length dimension of each cluster being transverse tothe longitudinal direction of conveyor displacement. To avoid confusion,the word longitudinal" herein refers only to the direction of theconveyor 10, i.e., to the flow direction of the conveyor, of thecontainers it carries, and of paperboard blanks which are continuouslyadvanced for assembly to conveyed clusters.

The invention is concerned with rapid comerbreaking and other automatichandling of paperboard blanks ll, successively taken from the lower endof a supply or magazine 12 (FIG. 1) and having a flat planform (FIG. 2)when stacked in and picked-off from the magazine 12. The blank 11comprises a centralpanel area 13 contiguous to and integral withlongitudinally opposed side-flange areas 14-15. Blank 11 is preferablyscored or otherwise locally weakened along desired ultimate parallelfold alignments l6l6'; spaced central openings 17 provide reinforcementfor finger access in inner spaces between containers of the six-pack, aswill be understood.

After pick-off from the magazine 12, each blank 11 is processed bypinch-roll means, designated generally 18, to corner-break thepaperboard at alignments l6-16'. The blank is then fed by auxiliaryconveyor means 19, including suitable guide means 20, to dis chargealmost tangent to the top of the next-to-becovered cluster, which, forthe instant depicted in FIG. 8, is the cluster M. Synchronized drive tothe endless chain means 21 of conveyor 19 and to the conveyor 10,

in the circumstance of conveyor-lug engagement to container clusters (at22) and of conveyor-lug engagement to blanks (at 23), assures perfectoverlay of the blanks on the tops of moving clusters. As shown, the feedlugs 23 of the auxiliary conveyor means 19 are provided as laterallyspaced pairs, for simultaneous engagement with the respective fingeropenings 17 of each blank 11.

In accordance with the invention, the pinch-roll means 18 establishesfirst and second pinching engagements, between continuously driven butoppositely rotated rolls which establish a first entering pinch region24 and a second entering pinch region 25, for ultimate discharge intosuitable guide means 26 for pick-up and displacement by the auxiliaryconveyor means 19.

The indicated pinch-roll action may be achieved by two pairs of pinchrolls, suitably positioned and driven to achieve the desired function;but, in the form shown, 1 indicate my preference for employment of acluster of three adjacent rolls 30-31-32, the first and last of whichare shown with an outer friction layer or surface, for no-slip pinch andfeed action on the work-piece or blank 11. Preferably also, all threerolls 30-31-32 are of substantially the same radius, which may be in theorder of magnitude of flange width W (FIG. 2), with the axes of thefirst pair 30-31 in a generally vertical or upstanding plane, and withthe axes of the second roll pair 31-32 in a transverse or generallyhorizontal plane. All three rolls 30-31-32 are continuously driven inopposite directions, as shown by arrows in FIG. 1 and as suggested bymeshing gears 30 -31 '-32 in other figures; such drive is synchronized(by means not shown) with drive to the conveyors 19-10.

Also synchronized with the indicated continuous drive system are tworeciprocating blank-engaging elements associated with the pinchmechanism 18. A first of these is a rod 33, spanning the overall lengthdimension X of blank 11, and positioned by like crank arms 34 at itsopposite ends; arms 34 are confined (by means to be later described) toreciprocating rotary gyration about the axis of the first roll 30. Suchreciprocation is intermittent, from a normal raised, at-rest position(shown in FIG. 1), to a transiently lowered, boardurging position closeto the pinch region 24 (shown in FIG. 4). The second blank-engagingmeans is an intermittently reciprocated elongated plate 35, alsosubstantially spanning the blank dimension X, and positioned by likearms 36 at its opposite ends; arms 36 are confined by a frame-basedpivot axis 37 and are driven in reciprocation (by means to be describedin connection with FIGS. 13 and 14), between a normally raised, atrestposition (shown in FIG. I), to a transiently lowered, board-urgingposition close to the pinch region (shown in FIG. 6).

A cradle is also carried by the arms 36 and forms part ofblank-positioning means after performing a first pinch and prior toperfonning the second pinch on each blank 11. As shown, the cradlecomprises spaced parallel angle members 38, defining upstanding lateralblank-guiding or locating surfaces 39 and slightly inclinedbottom-supporting flange surfaces 40, for the respective short ends ofthe blank 11. A tie piece 41 spans the arms 36 and carries a stop orangle member 42, poised to arrest a blank 11 as it is discharged fromrolls -31.

The corner-breaking action of the described pinch mechanism 18 will beunderstood from discussion of a cycle of handling one blank 11, inconnection with FIGS. 3 to 7. The blank 1 l is picked-off from the loweropen end of magazine 12, as by a swinging, intermittently reciprocatedstructure which carries vacuumoperated pick-off elements 43-44; theswing structure comprises two parallel spaced arms 45, pinned to anintermittently reciprocated shaft 46, and carrying elements 43-44 atlaterally offsetting brackets 47, at the ends of arms 45. As seen inFIG. 2, the vacuum pick-off engagements with blank 1 1 are laterallyoffset from the finger openings 17. Vacuum connection to pick-offs 43-44will be understood to be synchronized with the intermittentreciprocation of arms 45, such that pickoff engagement with a next blank1 1 occurs for the left position shown in FIG. 1, and such that suchengagement is maintained throughout swinging blankpositioningdisplacement into adjacency with the first two pinch rolls 30-31, asshown in FIG. 3; it is at this latter position that vacuum connection isinterrupted to release the hold on the blank 11 at 43-44. It will benoted that for movement to this position, the blank 11 will have clearedrod 33, which is still in its raised position, but which is immediatelyreciprocated down to its lower position (FIG. 4) and back (FIG. 5);also, it will be noted that at its lowered or second position, theblank-positioning means 43-44-45 will have placed the desired foldalignment 16 substantially in a generally horizontal plane that issubstantially tangent to adjacent pinch regions of rolls 30-31. In itsdescent to the FIG. 4 position, rod 33 intercepts blank 11 substantiallyat the desired fold alignment 16, and drives the same into the pinchregion 24, where, by friction engagement with the pinch rolls, the blankis not only pinched at 16 but is rapidly drawn through the rolls 30-31,to the point of arrest by stop 42 (FIG. 5).

Stop 42 is so offset from the pinch region 25 as to locate the seconddesired fold alignment 16' in substantially vertical register with thesecond pinch region 25 (i.e., substantially in the plane of tangency toadjacent regions of the second roll pair 31-32). And it will be notedthat the second blank-engaging means 35 is then poised for descent tocontact, depress and feed blank 11 (local to the desired alignment 16')into frictional pick-up by rolls 31-32 in the pinch region 25 (FIG. 6).Rolls 31-32 swiftly convey blank 11, in a reversed direction fordownward discharge, and in the course of such movement, the severelypinched first flange 14 (FIG. 6) is caused to strike and drag past thetie bar 35' by which plate 35 is connected to arms 36; such dragmoderates the fold of flange 14 to an obtuse, trailing angle, withrespect to the central-panel area 13, assuring that the comer-brokenedge at 16 will be no cause for fouling the mechanism.

Upon exit from the pinch mechanism 18, the blank is intercepted andguided by the spaced funneling rails or shoes 26 to spaced pairs offriction feed rolls 49-49, 50-50, forming part of the auxiliary conveyor19. Rolls 4949 are driven in synchronism with the endless chain means ofconveyor 19 and they stabilize blank 11 for synchronized entry of a feedlug 23. While the blank is thus conveyed, the roll pair 50-50 assumes afurther stabilizing function, during operation of a kicker 51, to extendthe flange 15, from a severe fold as shown in FIG. 8 at 15, for theblank 1 1 stabilized by rolls 49-49', to the much more obtuse angleshown at 15' for the immediately preceding blank 11'. The kicker 51 isshown as a roll or plate, having a large opening or notch in itsperiphery, said notch extending from a kicker leading edge 52 to atrailing edge 53. The kicker 51 is driven at a speed such that thekicking edge 52 engages the folded flange (15') at substantially greaterspeed than that of blank movement by conveyor 19. For example, for amaximum kicker diameter approximating that of feed roll 50, the drivespeed of kicker shaft 54 is conveniently twice that of the drive shafts55-56 for the stabilizing rolls W -50'. Having kicked flanges 15 ofsuccessive blanks just prior to engagement with guide means 20, there isno danger of fouling this leading flange (15), and properly coordinated,longitudinally centered application to passing clusters is assured.

The flanges 14-15 of blanks applied to successive clusters will benaturally and gently sloped down from the leading and trailing cornersof each cluster, as suggested in FIG. 8, for adjacent flanges 15-14 ofthe respective blanks applied to clusters M-L. This relation isconvenient for immediate locating control of the tops of all clusters,as by entry of suitably spaced stabilizing bars 57 carried by an endlessoverhead conveyor system 58; conveyor 58 may be driven by means 59 insynchronism with drive to conveyor 10. It will be understood thatconveyor 58 (and its bars 57) extendssufficiently to assure control ofcluster tops and their registering folded blanks 11, until introductionof plastic sheet for package-wrapping, all as described in saidapplication. After wrapping, including oven-shrinking, the envelopingplastic sheet 60 is drawn tightly over the containers and flanges 14-15and has the appearance of cluster A in FIG. 8.

Having thus described the general arrangement and operation of my methodand apparatus, I shall give further specific detail for the particularpreferred form shown.

The magazine 12 comprises a rigid system of upper and lower elongatedcorner guide members 65-66, within which the stack of blanks 11 issecurely nested and guided, for gravity feed, to present the lowermostblank 1 1 for ready pick-off. Small retaining lugs or lips 67-68 at thedispensing end hold the stack in place and yet do not interfere withvacuum pick-off of the end blank 1.

The entire blank-pinching and feeding mechanism is contained betweenupstanding side frame members 70-71, which are shown only in FHGS. 9, 10and 12. Magazine 12 is carried by bars 72-73 spanning these framemembers, and the pick-off shaft 46 is journaled in both of them. Otheroperative shafts of the system are also journaled in these framemembers, including the exit-feed stabilizing-roll shafts 55-56 alreadyidentified, as well as shafts 74-75-76 for the pinch rolls 30-31-32, thekicker shaft 54, and the various further shafts 77-78-79-80 relied uponto establish the path of the endless chain means of conveyor 19. In FIG.9, the endless chain means 21 is seen to comprise two laterally spacedlike chain systems, spaced according to the finger-openings 17, forentry of transport lugs 23. It will be noted from FIGS. 1, 8 and 9 thatdrive sprockets 81-82 and their conveyor-chain counterparts 83-84 may bethe means whereby drive is imparted to the stabilizing rollers49-49'-50-50; preferably of larger diameter than sprockets 83-84, sothat friction-feed of blanks 11 is slightly and transiently in excess ofchainlug feed at 23, thus avoiding any real need to drag the blank 11against a lug. This feature will be seen to assure that the product willhave an unmarred look, and yet if something should happen to spoil theeffectiveness of such friction feed, the lugs 23 will always be properlyphased and placed to assure against a jam of blanks 11 in the mechanism.

In the case of shaft 54 in FIG. 9, pinion 85 will be understood tosuggest drive synchronized with the other drives but at the higher speedalready indicated. The interconnection of all other drives is suggestedat 86 on one outer side of the described framing 70-71, as for exampleto the sprockets 81%2 already identified.

FIG. 9 also illustrates the mounting of the intermittently reciprocatedarms 34 for bar 33. This is seen to comprise an enlarged hub or boss 87for each arm and rotatable on the pinch-roll drive shaft 74. Collars 88stabilize the central position of bar 33, and a gear train 89-90 is themeans whereby intermittent reciprocation is transmitted to bar 33. Thisintermittent motion is generated by mechanism which best appears inFIGS. 10, 11 and 14. Basically, one of the continuous-drive pick-offsprockets 91 and its shaft 92 are used for camdrive purposes; and theshaft 92 performs the further function of establishing fixed-axisfree-pivot support of arms 36 of the second blank-engaging means, forwhich the fixed-axis pivot hub has already been identified at 37 inFIG. 1. A first plate cam 93 driven by shaft 92 imparts rocking motionto an arm 94, having one end fixedly pivoted at 95 to frame member 71,and having a follower roll 96 tracking cam 93; frame-based spring means97 normally urges such follower-tracking. The reciprocating motion ofthe end of arm 94 is transmitted by a link 98 to the gear 89, and a.substantially 2:1 gear step-up ratio at 89-90 assures rapid descent ofarm 34 (with rod 33) when the new blank 11 is to be fed at its score 16to the first pinch zone 24.

Intermittent rotary reciprocation for the second blank-engaging means 35is derived from a second plate cam 100 fastened to the same cam shaft92, and the entire mechanism is best seen in FIGS. 10,13 and 14.Basically, a cam pick-ofi pivot arm 101 is fixedly pivoted at 102 to theframe member 71. This arm 101 is equipped with a follower roll 103,urged by a frarnebased spring 104 to constantly track the cam profile. Alink 105 connects the free end of arm 101 to a correspondingly offsetback end 36' of the arm system 36. Thus, as cam 100 rises from the dwellon which follower 103 is shown in FIG. 13, link 105 is drawn upward, torock arm 36 downwardly, for transient blankengagement and depression atthe alignment 16'.

It will be seen that I have described a basically simple system forefficient corner-breakage and wellsynchronized feeding and control of apaperboard blank of the character indicated, meeting all stated objects.Of particular importance is the fact that by adapting the paperboardhandling mechanism of this invention to the shrink-wrapping mechanism ofsaid application, there is not the slightest limitation upon orimpairment of the speed or efficiency of shrink wrapping.

What is claimed is:

1. Mechanism for automatically comer-breaking the side-flange edges of apaperboard blank having a central-panel area contiguous to and integralwith longitudinally opposed side-flange areas, comprising blanksupplymeans presenting successive blanks at a pick-off location, firstpinch-roll means establishing a first pinching and longitudinallyfeeding plane substantially tangent to adjacent oppositely drivensurfaces of a first pair of rolls, first blank-positioning means fororienting a blank adjacent said roll surfaces and with a first desiredcorner-break alignment substantially in said tangent plane, said firstblank-positioning means including reciprocating means having a firstposition of pick-off engagement with the presented end blank at saidpickoff location, said reciprocating means being movable to a secondposition in which the picked-off blank is oriented adjacent the rollsurfaces of said first pinch-roll means and with the first desiredcomer-break alignment substantially in said first-mentioned tangentplane, blank-engaging means local to substantially said first alignmentwhen thus positioned and movable to advance the blank into frictionalengagement with said first roll means, means continuously driving saidfirst roll means in the direction to pinch and feed the blank alongsubstantially the tangent plane to the other side of said first rollmeans, second pinch-roll means establishing a second pinching andlongitudinally feeding plane substantially tangent to adjacentoppositely driven surfaces of a second pair of rolls, secondblankpositioning means arresting the blank and orienting the sameadjacent roll surfaces of said second roll means and with the seconddesired comer-break alignment substantially in said second-mentionedtangent plane, blank-engaging means local to substantially said secondalignment when thus positioned and movable to advance the blank intofrictional engagement with said second roll means, and meanscontinuously driving said second roll means in the direction to pinchand feed the blank along substantially the second tangent plane to theother side of said second roll means.

2. Mechanism according to claim 1, in which said tangent planes are insubstantially transverse relation, the second-mentioned transverse planeintersecting the first-mentioned transverse plane on said other side ofsaid first roll means. a

3. Mechanism according to claim 1, in which said first and secondpinch-roll means collectively comprise three rolls, the first and secondof said three defining said first pinch-roll means, and the second andthird of said three defining said second pinch-roll means.

4. Mechanism according to claim 3, in which said rolls are allcylindrical and in which the plane of the axes of the first two of saidthree rolls is substantially transverse to the plane of the axes of thesecond and third of said three rolls.

5. Mechanism according to claim 1, in which said reciprocating meansincludes a vacuum pick-off element, and means synchronized with themovement of said reciprocating means and controlling vacuum-operation ofsaid pick-off element for blank-holding throughout movement from thefirst to second positions of said reciprocating means.

6. Mechanism according to claim 5, in which said last-defined meansincludes means synchronized with operation of said first-mentionedblank-engaging means for determining blank-release by said pick-offelement as said first-mentioned blank-engaging means begins to advancethe blank into frictional engagement with said first roll means.

7. Mechanism according to claim 5, including means actuating saidfirst-mentioned blank-engaging means in synchronized interlace withmovement of said reciprocating means, said first-mentionedblank-engaging means being actuated in the blank-engaging andblankdisplacing direction when said reciprocating means attainssubstantially the second position thereof.

8. Mechanism according to claim 7, including means actuating saidsecond-mentioned blank-engaging means in synchronized interlace withmovement of said first-mentioned blank-engaging means, saidsecondmentioned blank-engaging means being actuated in theblank-engaging and blankdisplacing direction when the blank is beingpositioned by said second blankpositioning means.

9. Mechanism according to claim 2, in which said secondblank-positioning means includes a stop operative to retain a blankpassed through said first roll means.

10. Mechanism according to claim 4, in which the first-mentioned tangentplane is generally horizontal and said second pinch-roll means isbeneath said firstmentioned tangent plane, with the third of said threerolls substantially tangent to said first-mentioned tangent plane, saidsecond blank-positioning means including a stop operative to arrestblank movement after it has cleared the pinch region of said first rollmeans and with the blank supported at least in part by said third roll.

11. Mechanism according to claim 1, in which a single drive providesboth said drive means.

12. Mechanism according to claim 1, in which all rolls of said first andsecond pinch-roll means are cylindrical and of substantially the samediameter.

13. Mechanism according to claim 12, in which all rolls of said firstand second pinch-roll means have external surfaces of friction material.

14. Mechanism according to claim 1, in which said blank-supply meanscomprises a magazine for retaining a plurality of flat blanks, thepick-off location being at one end of said magazine.

15. Mechanism for automatically comer-breaking the side-flange edges ofa paperboard blank having a central-panel area contiguous to andintegral with longitudinally opposed side-flange areas, comprising firstpinch-roll means establishing a first pinching and longitudinallyfeeding plane substantially tangent to adjacent oppositely drivensurfaces of a first pair of rolls, first blank-positioning means fororienting a blank adjacent said roll surfaces and with a first desiredcomerbreak alignment substantially in said tangent plane, blank-engagingmeans local to substantially said first alignment when thus positionedand movable to advance the blank into frictional engagement with saidfirst roll means, means continuously driving said first roll means inthe direction to pinch and feed the blank along substantially thetangent plane to the other side of said first roll means, secondpinch-roll means establishing a second pinching and longitudinallyfeeding plane substantially tangent to adjacent oppositely drivensurfaces of a second pair of rolls, second blank positioning meansarresting the blank and orienting the same adjacent roll surface of saidsecond roll means and with the second desired comer-break alignmentsubstantially in said secondmentioned tangent plane, blank-engagingmeans local to substantially said second alignment when thus positionedand movable to advance the blank into frictional engagement with said scond rolls means, means continuously driving said second roll means inthe direction to pinch and feed the blank along substantially the secondtangent plane to the other side of said second roll means, conveyormeans in synchronism with said drive means and engaging and advancingsuccessive blanks discharged from said second roll means, andflange-kicker means on the flange-folded side of said conveyor means andsynchronized with blank-conveying movement to engage flanges bent bysaid second roll means and kicking them in the unbending direction.

16. The method of automatically cornenbreaking the side-flange edges ofa paperboard blank having a central-panel area contiguous to andintegral with longitudinally opposed side-flange areas, which comprisesselecting three pinch rolls of radius approximating the longitudinalextent of the side-flange areas, orienting said rolls in side-by-sideadjacency on parallel axes such that the orientation plane of axes forthe first two rolls is substantially transverse to the orientation planeof axes for the second and third rolls, continuously rotating all saidrolls with adjacent rolls rotating in opposite directions, positioningan unbroken blank substantially parallel to the first plane and adjacentthe first two rolls with the desired comer-break alignment substantiallyin the plane of tangency to adjacent pinch regions of the first tworolls, said first two rolls being driven in the directions to pinch anddraw the blank between said first two rolls, locally urging said blankin the region of said comer-break alignment into frictional engagementwith said first two rolls, whereby a first side-flange area is pinchedand folded back against the central-panel area of the blank as the blankis fed between said first two rolls, arresting said blank afterlongitudinal feed thereof by said first two rolls and at a locationpositioning said blank. adjacent the second and third rolls with thesecond desired corner-break alignment substantially in the plane oftangency to adjacent pinch regions of the second and third rolls,locally urging said blank in the region of said second corner-breakalignment into frictional engagement with the second and third of saidrolls, whereby the second side-flange area is pinched and folded backagainst the central-panel area of the blank as the blank is fed betweensaid second and third rolls, providing a supply of blanks available forpick-off of successive blanks from an end of the supply, andsuccessively picking-off and transferring successive blanks from saidend and into the position adjacent the first two rolls.

17. The method of claim 16, including the preliminary step of scoringthe blank on one side and along both the desired comer-break alignments.

18. The methodof claim 16, in which the orientation of roll axes ishorizontal, with the third roll beneath and substantially tangent to theplane of tangency to adjacent pinch regions of the first two rolls,whereby blank discharge is downward upon passage by the second and thirdrolls.

1. Mechanism for automatically corner-breaking the side-flange edges ofa paperboard blank having a central-panel area contiguous to andintegral with longitudinally opposed sideflange areas, comprisingblank-supply means presenting successive blanks at a pick-off location,first pinch-roll means establishing a first pinching and longitudinallyfeeding plane substantially tangent to adjacent oppositely drivensurfaces of a first pair of rolls, first blank-positioning means fororienting a blank adjacent said roll surfaces and with a first desiredcorner-break alignment substantially in said tangent plane, said firstblank-positioning means including reciprocating means having a firstposition of pick-off engagement with the presented end blank at saidpick-off location, said reciprocating means being movable to a secondposition in which the picked-off blank is oriented adjacent the rollsurfaces of said first pinch-roll means and with the first desiredcorner-break alignment substantially in said first-mentioned tangentplane, blankengaging means local to substantially said first alignmentwhen thus positioned and movable to advance the blank into frictionalengagement with said first roll means, means continuously driving saidfirst roll means in the direction to pinch and feed the blank alongsubstantially the tangent plane to the other side of said first rollmeans, second pinch-roll means establishing a second pinching andlongitudinally feeding plane substantially tangent to adjacentoppositely driven surfaces of a second pair of rolls, secondblank-positioning means arresting the blank and orienting the sameadjacent roll surfaces of said second roll means and with the seconddesired corner-break alignment substantially in said second-mentionedTangent plane, blankengaging means local to substantially said secondalignment when thus positioned and movable to advance the blank intofrictional engagement with said second roll means, and meanscontinuously driving said second roll means in the direction to pinchand feed the blank along substantially the second tangent plane to theother side of said second roll means.
 2. Mechanism according to claim 1,in which said tangent planes are in substantially transverse relation,the second-mentioned transverse plane intersecting the first-mentionedtransverse plane on said other side of said first roll means. 3.Mechanism according to claim 1, in which said first and secondpinch-roll means collectively comprise three rolls, the first and secondof said three defining said first pinch-roll means, and the second andthird of said three defining said second pinch-roll means.
 4. Mechanismaccording to claim 3, in which said rolls are all cylindrical and inwhich the plane of the axes of the first two of said three rolls issubstantially transverse to the plane of the axes of the second andthird of said three rolls.
 5. Mechanism according to claim 1, in whichsaid reciprocating means includes a vacuum pick-off element, and meanssynchronized with the movement of said reciprocating means andcontrolling vacuum-operation of said pick-off element for blank-holdingthroughout movement from the first to second positions of saidreciprocating means.
 6. Mechanism according to claim 5, in which saidlast-defined means includes means synchronized with operation of saidfirst-mentioned blank-engaging means for determining blank-release bysaid pick-off element as said first-mentioned blank-engaging meansbegins to advance the blank into frictional engagement with said firstroll means.
 7. Mechanism according to claim 5, including means actuatingsaid first-mentioned blank-engaging means in synchronized interlace withmovement of said reciprocating means, said first-mentionedblank-engaging means being actuated in the blank-engaging andblank-displacing direction when said reciprocating means attainssubstantially the second position thereof.
 8. Mechanism according toclaim 7, including means actuating said second-mentioned blank-engagingmeans in synchronized interlace with movement of said first-mentionedblank-engaging means, said second-mentioned blank-engaging means beingactuated in the blank-engaging and blank-displacing direction when theblank is being positioned by said second blank-positioning means. 9.Mechanism according to claim 2, in which said second blank-positioningmeans includes a stop operative to retain a blank passed through saidfirst roll means.
 10. Mechanism according to claim 4, in which thefirst-mentioned tangent plane is generally horizontal and said secondpinch-roll means is beneath said first-mentioned tangent plane, with thethird of said three rolls substantially tangent to said first-mentionedtangent plane, said second blank-positioning means including a stopoperative to arrest blank movement after it has cleared the pinch regionof said first roll means and with the blank supported at least in partby said third roll.
 11. Mechanism according to claim 1, in which asingle drive provides both said drive means.
 12. Mechanism according toclaim 1, in which all rolls of said first and second pinch-roll meansare cylindrical and of substantially the same diameter.
 13. Mechanismaccording to claim 12, in which all rolls of said first and secondpinch-roll means have external surfaces of friction material. 14.Mechanism according to claim 1, in which said blank-supply meanscomprises a magazine for retaining a plurality of flat blanks, thepick-off location being at one end of said magazine.
 15. Mechanism forautomatically corner-breaking the side-flange edges of a paperboardblank having a central-panel area contiguous to and integral withlongitudinally opposed side-flange areas, comprising first piNch-rollmeans establishing a first pinching and longitudinally feeding planesubstantially tangent to adjacent oppositely driven surfaces of a firstpair of rolls, first blank-positioning means for orienting a blankadjacent said roll surfaces and with a first desired corner-breakalignment substantially in said tangent plane, blank-engaging meanslocal to substantially said first alignment when thus positioned andmovable to advance the blank into frictional engagement with said firstroll means, means continuously driving said first roll means in thedirection to pinch and feed the blank along substantially the tangentplane to the other side of said first roll means, second pinch-rollmeans establishing a second pinching and longitudinally feeding planesubstantially tangent to adjacent oppositely driven surfaces of a secondpair of rolls, second blank-positioning means arresting the blank andorienting the same adjacent roll surface of said second roll means andwith the second desired corner-break alignment substantially in saidsecond-mentioned tangent plane, blank-engaging means local tosubstantially said second alignment when thus positioned and movable toadvance the blank into frictional engagement with said second rollsmeans, means continuously driving said second roll means in thedirection to pinch and feed the blank along substantially the secondtangent plane to the other side of said second roll means, conveyormeans in synchronism with said drive means and engaging and advancingsuccessive blanks discharged from said second roll means, andflange-kicker means on the flange-folded side of said conveyor means andsynchronized with blank-conveying movement to engage flanges bent bysaid second roll means and kicking them in the unbending direction. 16.The method of automatically corner-breaking the side-flange edges of apaperboard blank having a central-panel area contiguous to and integralwith longitudinally opposed side-flange areas, which comprises selectingthree pinch rolls of radius approximating the longitudinal extent of theside-flange areas, orienting said rolls in side-by-side adjacency onparallel axes such that the orientation plane of axes for the first tworolls is substantially transverse to the orientation plane of axes forthe second and third rolls, continuously rotating all said rolls withadjacent rolls rotating in opposite directions, positioning an unbrokenblank substantially parallel to the first plane and adjacent the firsttwo rolls with the desired corner-break alignment substantially in theplane of tangency to adjacent pinch regions of the first two rolls, saidfirst two rolls being driven in the directions to pinch and draw theblank between said first two rolls, locally urging said blank in theregion of said corner-break alignment into frictional engagement withsaid first two rolls, whereby a first side-flange area is pinched andfolded back against the central-panel area of the blank as the blank isfed between said first two rolls, arresting said blank afterlongitudinal feed thereof by said first two rolls and at a locationpositioning said blank adjacent the second and third rolls with thesecond desired corner-break alignment substantially in the plane oftangency to adjacent pinch regions of the second and third rolls,locally urging said blank in the region of said second corner-breakalignment into frictional engagement with the second and third of saidrolls, whereby the second side-flange area is pinched and folded backagainst the central-panel area of the blank as the blank is fed betweensaid second and third rolls, providing a supply of blanks available forpick-off of successive blanks from an end of the supply, andsuccessively picking-off and transferring successive blanks from saidend and into the position adjacent the first two rolls.
 17. The methodof claim 16, including the preliminary step of scoring the blank on oneside and along both the desired corner-break alignments.
 18. The meThodof claim 16, in which the orientation of roll axes is horizontal, withthe third roll beneath and substantially tangent to the plane oftangency to adjacent pinch regions of the first two rolls, whereby blankdischarge is downward upon passage by the second and third rolls.